In work shops where heavy industrial manufacturing processes such as welding are carried out, there may be significant quantities of fumes, gases, vapours or other contaminants being produced which must be exhausted away from the work area. The present invention is not directed to systems for scrubbing or neutralizing the fumes or other noxious gases, but it is directed to a system whereby as much as is possible capture of the fumes being generated is accomplished.
Generally, exhaust systems may comprise an exhaust duct which may be articulated having two or three sections, or it may be flexible and suspended from an articulated support frame. In either event, a fume hood is provided at the forward end of the exhaust duct and a fan is provided at the rear end of the exhaust duct. When the fan is operated, a vacuum is created in the area of the fume hood, so as to extract the fumes being generated in the area of the fume hood and below it.
Whether the fan, and thereby the rear end of the exhaust duct, is mounted on a moveable cart or is fixed, is immaterial to the present invention. What is important is that the fume extraction system provided by the present invention may be placed in any convenient place near the work tool, or vice versa, so as to accomplish fume extraction.
Generally, it is best to effect fume or contaminant extraction from near the source of the contaminant. The contaminants may be simply gasses, they may include dust particles and other small particles such as weld splatter or paint droplets, and so on. The use of local fume extraction is particularly attractive when the alternatives are considered; they may include high volume fresh air circulation where gross exchange of air volume is effected, or other updraft or exhaust systems which may be particularly useful in spray paint booths and the like, but not at all useful in environments such as a welding shop. Moreover, in any work place having a large floor area and/or a high work area, the cost of gross air exchange is prohibitive. Still further, cross drafts may be created, which in some instances may result in the contaminants generated in the work area being blown directly at the workers in the area.
There have been developed remote exhaust arms that may be positioned over the source of the contaminants; and several such systems are discussed below. One of the concerns in general with the prior art systems has been that every time the work tool or workpiece is moved beyond the effective range of the fume hood, the fume hood or the workpiece must be re-positioned. While this may be acceptable for certain kinds of static work, it is clearly not acceptable for work such as welding where the tool may be moved within a limited range but beyond the effective range of the fume hood. Any requirement for the work tool and the workpiece to be moved to accommodate the limitations of contaminant extraction reduces the efficiency of the work being done, or the efficiency of the worker, and is therefore unacceptable.
The present invention recognizes that a reasonably large area can be defined (limited only by the specific dimensions of the apparatus provided by this invention), whereby any work being done within that prescribed area can be automatically tracked by the exhaust system so that the fume hood is always located in a position relative to the work in order that the maximum fume extraction that can be accomplished is achieved. By the present invention, an autotracking fume extraction exhaust hood is provided that does not require any manual re-positioning of the hood or the work tool within the working area prescribed for the apparatus, thereby significantly improving the efficiency of the work and of the worker. This is particularly effective in the circumstances where the worker is using a hand held tool, such as is most common in a welding operation.